Heat sterilization is the preferred method to disinfect or sterilize items and surfaces that need to be germ-free during use, such as surgical and dental instruments and environmental surfaces utilized in these environments. Unfortunately, heat treatment is not acceptable for some materials, like rubber gloves, thermometers and other heat-degradable or heat-sensitive instruments and surfaces that are usually found in medical and dental environments. Heat is also not usually appropriate for surface areas of tables, chairs, sinks and the like which actually comprise the environment which must be kept substantially germ-free. These must be treated using chemical disinfectants and sterilants.
Sterilant solutions have been used for many years to disinfect and sterilize medical instruments, dental instruments and other articles, tools, and surfaces that must be germ-free during operation or use. Sterilant solutions may also be used to disinfect and treat medical and other wastes that may pose a environmental hazard if not disposed of properly. These solutions are primarily aqueous in nature and comprise a low concentration of a highly potent germicide.
In the past, sterilant solutions have been purchased in dilute liquid form and applied directly to the surface to be treated. These dilute aqueous solutions are heavy, difficult to store, cumbersome and are subject to spillage and degradation. Concentrating these aqueous solutions is not an adequate remedy as it still results in difficult bulk transportation and safety problems.
Concentrated sterilants, in the form of solids or semi-solids, would avoid the difficulties and safety concerns inherent in storing and moving large volumes of dilute aqueous sterilant solutions. This highly concentrated form of the sterilant takes up far less space, is less bulky and there is a lesser probability of spillage and loss. The difficulty with some concentrated systems however, is that many sterilants in this state will not readily dissolve to form an aqueous solution.
Types of known sterilant solutions are dilute aqueous solutions of a strong effective crosslinking agent, one class being the dialdehydes. One common dialdehyde that is particularly effective in this fashion is glutaraldehyde whose chemical structure is as follows: EQU O.dbd.CH--CH.sub.2 --CH.sub.2 --CH.sub.2 --CH.dbd.O
Conventional glutaraldehyde sterilant systems usually comprise only about 2.0% by weight of glutaraldehyde. Additionally, these systems often contain a non-ionic surfactant, a chelating agent, and a buffer. An object to be sterilized is simply immersed into the solution as with surgical and dental instruments, or the solution is applied by any one of a number of means to a surface to be sterilized such as surgical platforms or dental side tables.
One glutaraldehyde sterilant system is set forth in U.S. Pat. No. 5,284,621 to Kaufman, issued Feb. 8, 1994. That patent discloses treatment of medical waste fluids using a xerogel comprised of at least one water insoluble hydrophilic polymer and glutaraldehyde. The xerogel absorbs aqueous ingredients in waste fluids, and the glutaraldehyde disinfects the fluids. The patent discloses that the glutaraldehyde may be formulated as a bisulfite addition product in a solid form such as free-flowing powders so as to prevent reaction with the xerogel prior to use, yet would decompose upon exposure to the mildly acidic or alkaline conditions of the waste fluids. Unfortunately, aldehydes (i.e. glutaraldehyde) are fairly reactive and have a tendency to react with the xerogels disclosed and claimed in this patent. To avoid reaction of the glutaraldehyde with the xerogels, the disclosure teaches that such problems might be precluded by using solid derivatives of the disinfectants which would not be reactive with the xerogels. These derivatives could then be effectively distributed throughout the xerogel and could easily decompose and be released upon contact with the waste fluids to yield the desired disinfectant. Suggested suitable derivatives include the bisulfite addition products of carbonyl group-containing compounds such as glutaraldehyde which are easily decomposed to form the carbonyl group containing composition and the bisulfite under the mildly acidic or alkaline conditions usually found in the collected fluids.
Another patent, U.S. Pat. No. 3,983,252 to Buchalter, issued Sep. 28, 1976 is directed to disinfectant compositions that contain a dialdehyde and the alkali metal salt of a hydrocarbon carboxylic acid in aqueous solution and, optionally, an alcohol and/or a diol and/or a triol. The dialdehyde may be in its pure form, its acid form or in the form of an adduct such as an alkali metal bisulfite adduct, glutaraldehyde bisulfite. The disinfectant may also comprise a nitrogenous adduct such as glutaraldehyde dioxime. Although the main goal of the patent is the long term stability of aqueous glutaraldehyde formulations, the dialdehyde component may also be formulated as a solid.
Glutaraldehyde has also been used for purposes other than disinfection such as functioning as a stabilizer in color photographic film.
Despite the known use of glutaraldehyde as a sterilant and/or disinfectant, and despite the known use of solid glutaraldehyde derivatives in treating waste fluids, there is a strong need in the art for a concentrated, solid or semi-solid sterilant composition with several important properties never before provided by the prior art. In order for a solid or semi-solid sterilant to be of any value, the composition must be sufficiently stable to avoid decomposition during long term storage and it must be substantially impervious to the presence of moisture. On the other hand however, the composition must also be sufficiently reactive when mixed in solution to generate an effective dose of glutaraldehyde in a timely fashion as needed. The compositions must also be relatively safe to handle. And, preferably, the composition should be commercially available, or at least easily and reliably synthesized from commercially available materials.
Most importantly, however, the source of glutaraldehyde must be readily solubilized and activated as a sterilant solution with the reactive aldehyde groups not degraded or complexed with other ions during this solubilizing and mixing process.